1. Field of the Invention
The invention relates to a method for the production of a piston for an internal combustion engine, in accordance with the preamble of claim 1.
2. The Prior Art
From the state of the art, it is generally known to produce pistons from steel for an internal combustion engine, in that first an upper piston part is produced using the forging method, and a lower piston part is produced using the forging method or by means of casting, and then the upper piston part is welded to the lower piston part. In this regard, reference should be made to the patent documents DE 195 01 416 A1, DE-OS 29 19 638, DE 196 03 589 A1, and DE 198 46 152 A1. In this connection, the method of hot forming, in other words hot forging, at a steel temperature of 950° C. to 1300° C., is used.
This method has the disadvantages that a great expenditure of energy is required for heating the forged blank. Furthermore, an uncontrollable oxide layer forms on the surface of the forged blank, and in order to remove it, the surface of the forged blank must be blasted with coarse blasting material. This results in great variations in the forged contour, so that as a consequence of this, complicated reworking of the forged blank, by means of a chip-cutting processing method, is required.